31. Mechanical properties of Teeth and parts of the Supportive Locomotor Systemrename
yaboiemil's version from 2016-01-26 16:44
Section1. You have 20 Baby teeth
2. You have 32 Adult Teeth
3. Max force is 650N.
4. Max Pressure is 40MPa
5. The structure of a tooth is the Crown, Neck and Root. The crown is covered in Enamel.
5. Bone's Middle is the Diaphysis
6. Bone's end are the Epiphysis
7. Diaphysis is hollow to resist deformation
8. Epiphysis filled with stroma, arranged to withstand the most frequent directional forces
9. Wolf's Law of Deformation: Bone structure adapts to a permanent change in acting forces.
10. A lack of any loading results in high excretion of Ca20+ in the human body (e.g. astronauts in weightlessness)
11. Bone are joined by joints.
12. Several Bones and joints usually work together in a kinematic chain to allow full range of movement and speed of movement.
13. Muscle contraction can be:
|Isotonic||Muscle is shortened when it contracts|
|Isometric||Muscle remains the same length but still is doing work|
Muscle contraction Mechanism:
14. Acetylcholine conducts an impulse from the motor end plate (e.d of motor neurone) to muscle. K+ ions flow in.
15. It is proved that the more dense bone tissue is, the less likely it is to result in a pathological fracture.
16. Density of bone can be measured in 2 ways:
|X-ray Densiometry||x-rays are absorbed by bone tissue, allow you to see mineral content and density.|
|Ultrasound Densiometry||Measured speed and attenuation of ultrasound through bone tissue.|
17.X-ray has the disadvantages of being expensive, ionising radiation and gives limited information
18.Ultrasound has the advantages of being harmless and provides more information on the structure of the bone tissue
and it's elastic properties.